import autolinkHeadings from 'rehype-autolink-headings'
import { toString } from 'hast-util-to-string'
import { h } from 'hastscript'

// Documentation can be found at https://github.com/rehypejs/rehype-autolink-headings
const AnchorLinkIcon = h(
  'svg',
  {
    width: 24,
    height: 24,
    version: 1.1,
    viewBox: '0 0 16 16',
    xlmns: 'http://www.w3.org/2000/svg',
  },
  h('path', {
    fillRule: 'evenodd',
    fill: 'currentcolor',
    d: 'M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z',
  }),
)

const createSROnlyLabel = (text) => {
  const node = h('span.sr-only', `Section titled ${escape(text)}`)
  node.properties['is:raw'] = true
  return node
}

const options = {
  behavior: 'append',
  content: (heading) => [
    h(
      `span.anchor-icon`,
      {
        ariaHidden: 'true',
      },
      AnchorLinkIcon,
    ),
    createSROnlyLabel(toString(heading)),
  ],
}

export const autolinkHeadingsPlugin = [autolinkHeadings, options]
